Ibai Coria Martínez

• Mechanical Engineer
• Lecturer and researcher at University of the Basque Country

In this work, a new algorithm for solving symmetric indefinite systems of linear equations is presented. It factorizes the matrix into the form LDLt using Jacobi rotations in order to increase the pivot's absolute value. Furthermore, Rook's pivoting strategy is also adapted and implemented. In determinate compatible systems, the computational cost...

Statement of problem. Dental implant geometry affects the mechanical performance and fatigue behavior of butt-joint implant-supported restorations. However, failure of the implant component has been generally studied by ignoring the prosthetic screw, which is frequently the critical restoration component Purpose. Evaluate the effect of 3 main impla...

Since Erich Franke produced the first wire race bearings in 1934, they have not been used profusely until these last years in applications such as computerized tomography, X-ray machines, wheels with direct drive... where low weight and inertia constraints are important. Accounting for the structural behaviour of the bearing, there exist a key phen...

In wire bearings the rolling process occurs on raceways machined on steel wires, and the rings are made of light materials such as aluminium. This particular architecture provides both weight and inertia savings, but also significantly different behaviour with respect to conventional bearings. For this reason, specific design and analysis tools mus...

Statement of problem. Cold rolling is widely used for screw thread manufacturing in industry but is less common in implant dentistry, where cutting is the preferred manufacturing method. Purpose. The purpose of this in vitro study was to compare the surface finish and mechanical performance of a specific model of prosthetic screw used for direct re...

This work introduces a methodology for the calculation of the load distribution in four-point contact slewing bearings considering ball preload, manufacturing errors and ring flexibility. The model is built by the formulation and minimization of the potential energy of the bearing. Comparing with the rigid rings assumption, the results show that ri...

Since wire bearings were patented in 1936, they have been used in applications where weight saving is a key aspect. Nevertheless, little work can be found in literature regarding their structural behaviour. In order to predict how a wire bearing reacts under load, the most feasible way is to model and analyse it via Finite Elements (FE). However, t...

Several factors can cause leakages in a bolted flange connection, external loads being the most important one. External loads such as those produced by misalignment introduce an external axial load combined with a bending moment which could lead to either an excessive compression of the gasket and its subsequent crushing, and/or a separation of the...

There are several common procedures used to numerically integrate second-order ordinary differential equations. The most common one is to reduce the equation’s order by duplicating the number of variables. This allows one to take advantage of the family of Runge–Kutta methods or the Adams family of multi-step methods. Another approach is the use of...

As screwed joints, dental restorations may suffer mechanical failures such as screw loosening and implant or prosthetic screw failure due to fatigue. This work is focused on the failure of the implant and develops a numerical methodology to predict its fatigue life under cyclic loading conditions. This methodology is based on the combination of Cri...

Apart from other options, a common procedure to integrate order 2 Ordinary Differential Equations (ODEs) present in Multibody systems is to reduce the order of the ODE by duplicating the number of variables. This leads to apply the well-known family of Runge-Kutta (RK) methods. Other approach, commonly used in structural mechanics, is the use of me...

Purpose: To evaluate the effect of implant body diameter, platform diameter, and the use of transepithelial components on implant-abutment connection (IAC) microgap width. Materials and methods: In total, 16 tests were performed on four commercial dental restoration models (BTI Biotechnology Institute). Different static loads were applied to the...

Statement of problem Dental implant geometry affects the mechanical performance and fatigue behavior of butt-joint implant-supported restorations. However, failure of the implant component has been generally studied by ignoring the prosthetic screw, which is frequently the critical restoration component. Purpose The purpose of this in vitro study...

Statement of problem Cold rolling is widely used for screw thread manufacturing in industry but is less common in implant dentistry, where cutting is the preferred manufacturing method. Purpose The purpose of this in vitro study was to compare the surface finish and mechanical performance of a specific model of prosthetic screw used for direct res...

Bolted joints are a critical component of machines and structures under cyclic loading. Bolt fatigue failure usually takes place in the first engaged thread for being the most loaded one. In this sense, a uniform thread load distribution improves its mechanical response and consequently the reliability of the joint. For this purpose, different thre...

Featured Application A methodology to study screw self-loosening phenomenon in preliminary design stages of dental implants is presented. Abstract Self-loosening of the prosthetic screws is a major mechanical problem affecting roughly 10% of dental implants, according to the literature. This phenomenon may lead to micro-movements that produce cres...

Fatigue is the most common mechanical failure type in dental implants. ISO 14801 standardizes fatigue testing of dental implants, providing the load-life curve which is most useful for comparing the fatigue behavior of different dental implant designs. Based on it, many works were published in the dental implant literature, comparing different mate...

When a bolt is tightened, significant dispersion between the target preload and the obtained preload may be found. As a consequence, when bolts are subsequently tightened during the assembly process of a bolted joint, the dispersion is propagated leading to a higher scatter in the final bolt load distribution. In this sense, the final bolt loads ma...

Since wire bearings were patented in 1936, they have been used in applications where weight saving is a key aspect. Nevertheless, little work can be found in literature regarding their structural behaviour. In order to predict how a wire bearing reacts under load, the most feasible way is to model and analyse it via Finite Elements (FE). However, t...

Since Erich Franke produced the first wire race bearings in 1934, they have not been used profusely until these last years in applications such as computerized tomography, X-ray machines, wheels with direct drive… where low weight and inertia constraints are important. Accounting for the structural behaviour of the bearing, there exist a key phenom...

This work introduces a methodology for the calculation of the load distribution in four-point contact slewing bearings considering ball preload, manufacturing errors and ring flexibility. The model is built by the formulation and minimization of the potential energy of the bearing. Comparing with the rigid rings assumption, the results show that ri...

Wire-race bearings are a non-conventional type of bearings where the rolling process takes place over a race shaped in a wire. This design allows building the rings with lighter materials and innovative ring designs. Despite the wide range of applications where wire-race bearings can be the best option, no specific analysis tools have been develope...

Nowadays, dental implant fatigue tests are commonly performed in direct stress fatigue test benches. Even though the accuracy of these machines is very high, they can only test one specimen simultaneously. Besides, taking into account that each test may last several days, a dental implant fatigue characterization may become a very costly task. Furt...

Uniform bolt load is critical to achieve leak-free service in pressure vessel gasketed joints. In a previous work, the authors presented the tetraparametric assembly method, which enabled to obtain a uniform final load distribution in a one-pass tightening sequence. The accuracy of the method was proved by finite element analysis and experimental t...

This work proposes an approach to calculate the load distribution among balls in a four-point contact slewing bearing considering manufacturing errors and ring stiffness. The model is established upon the formulation and minimization of the potential energy of the system. Calculations are done for a particular bearing considering different assumpti...

The stiffness of yaw and pitch slewing bearings has a critical influence on the structural behaviour of wind turbine generators. Thus, it is commonly required by designers for their simulations to estimate deformations and select the most suitable bearing for their working conditions in preliminary design stages. In this work, a design of experimen...

In wire bearings the rolling process occurs on raceways machined on steel wires, and the rings are made of light materials such as aluminium. This particular architecture provides both weight and inertia savings, but also significantly different behaviour with respect to conventional bearings. For this reason, specific design and analysis tools mus...

Misfit is unavoidable in dental implant-supported prostheses due to machining process or inappropriate assembling, and the definition of an admissible misfit is still a controversial issue. This work aims to understand the behavior of the screws in dental implant-supported prostheses to estimate an admissible vertical misfit value in terms of screw...

A lot of effort is put to achieve bolt preload uniformity during the assembly process of offshore bolted joint connections resulting in potentially high economic costs and project delays. The complexity of this operation is due to the effect of the elastic interaction between the different joint elements which causes load variations of adjacent bol...

Several factors can cause leakages in a bolted flange connection, external loads being the most important one. External loads such as those produced by misalignment introduce an external axial load combined with a bending moment which could lead to either an excessive compression of the gasket and its subsequent crushing, and/or a separation of the...

In this work, a superelement-based model is developed to study bolt load variations and gasket stress distribution during tightening sequences, in order to avoid damages in the assembly and achieve uniform gasket stress distribution. Besides, this model can also be used to study the response of gasketed joints under internal and external loads. To...

For pressure vessels gasketed joints, obtaining a uniform bolt load distribution is mandatory in order to ensure leak-free service of the joint. However, due to the elastic interaction phenomenon, it is difficult to achieve a uniform bolt load distribution. To address this difficulty, standards recommend tightening sequences that have shown good pe...

En el ensamblado de uniones bridadas con junta, obtener una carga uniforme en los tornillos es muy importante para evitar fugas a lo largo de su vida útil. Sin embargo, cuando un tornillo es precargado durante el proceso de ensamblado, la unión se comprime y el resto de los tornillos pierde parte de su carga dificultando significativamente la obten...

Achieving uniform bolt load distribution is critical to obtain leak-free service in pressure vessel gasketed joints used in offshore pipelines. This is a difficult task due to bolt load variations during the assembly process. In this sense, the Elastic Interaction Coefficients Method has been developed in previous works to define tightening sequenc...

This work presents a model to assess the equivalent load for self-lubricating radial spherical plain bearings under combined loads, based on the study of the interference field. Using an algorithm based on the model, a methodology has been created to estimate failure load combinations. The results, validated via Finite Element Analysis, are present...

In the assembly of gasketed joints, obtaining a uniform bolt load is essential to achieve leak-free service of the joint. Nevertheless, whenever a fastener is tightened during the assembly, the joint gets compressed and consequently the load in previously tightened fasteners is reduced, which makes it difficult to obtain the desired uniform bolt fo...

Several analytical models have been proposed to estimate the load distribution and the deformation of slewing bearing assemblies in wind turbine generators (WTGs). Even though they are a useful tool for designers as a first approach, most of them assume rigid rings and rigid supporting structures, leading to inaccurate results; even if compliance i...

The selection of slewing bearings is based on the static load-carrying capacity. In this sense, manufacturers provide selection curves in their catalogues. However, little information is given about their origin. This work develops new and more versatile selection curves for four contact point slewing bearings, with a clear explanation of their bac...

En los últimos años se han publicado varios métodos analíticos para estimar la distribución de cargas y la deformación de los ensamblajes de rodamientos de vuelco en aerogeneradores. Pese a ser útiles para obtener resultados preliminares, la mayoría de estos métodos supone anillos y estructuras de soporte rígidos, lo cual conduce a resultados impre...